Migrated user and email address changed. How do I keep it the same?

I'm about to migrate an exchange server to zimbra and i did a simulation on virtual machines, while the migration seemed to work, i noticed that the email address changed, and thats not what i need.

The address changed from user@domain.com to user@zimbra.domain.com, and while I don't care for what the mailbox is called, i care that the email address is the same, so I would like to ask everyone for some ideas on what I've done wrong. How do I keep it the same address that it was before?

You can create a new domain with correct name and then rename all the accounts to correct one.

zmprov cd <newdomain>

zmprov ra <wrongemailaddress> <correctemailaddress>

You may need to create a script if you have many accounts.

So, there is no way to avoid that? if i have to create a new domain, why not create the domain before the migration and then import users to the new domain? seems like the migration process is not really that good if thats the only option. Keep in mind i've used a fake domain to test it, I can do this again if needed.

Should I do anything different on the install process?

I'm just trying to get as much info as i can before the real migration.

Make sure you create the same domain as the one on exchange server.
Looks like you had "zimbra.domain.com" domain instead of "domain.com". You can edit the domain name at the time of installation at configuration window.